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\begin{document}

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\lhead{Chenyue (22035026)}
\chead{math story one}
\rhead{Date}


\section*{I. Briefly repeat the problem}

\subsection*{I-a} 

This is my idea.

for example:ssss

\subsection*{I-b} 

\section*{II. Briefly repeat the problem}

Give your answers here.


\end{document}

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